Device for processing the surface of spherical shells

ABSTRACT

This disclosure concerns a device for machining surfaces, e.g., superfinishing, polishing, grinding or lapping spherical shells or flattened domes of a workpiece, or, for example, a ball joint, using a tool having a machining stone with a workpiece receiver, a first drive for an oscillating motion about a first axis of the workpiece, a tool holder and a second drive for an oscillating motion about a second axis of the tool holder, whereby the axes are an angle to one another.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/077,298, filed on Jul. 1, 2008, the contents of which are incorporated herein by reference.

FIELD

The present disclosure relates to a device for processing surfaces.

BACKGROUND

In various cutting forms of processing, such as for example, superfinishing, honing, slotting and planing, the tool executes an oscillating motion.

SUMMARY

The present disclosure concerns a device for processing surfaces, especially for superfinishing, polishing, grinding or lapping spherical shells for a workpiece having a flattened dome or flattened dome sections using a tool having a machining stone with a workpiece receiver and a tool holder, each with a respective drive.

It is generally known that, as with other machining methods, a tool is brought into contact with a workpiece in the superfinishing method as well. By superposing the workpiece rotation and workpiece oscillation, for example, a single grain moves along a sinusoid curve typical of this method. By superposing the individual sinusoidal lines, all meshing polishing grains generate the processing traces intersecting at a defined angle. Since the tool is applied onto the workpiece at a specified pressure, care must be taken that the contact of the tool with the workpiece is not interrupted, namely that the tool does not leave the surface to be processed, as the tool has to be lifted prior to leaving the surface and would have to be subsequently put on it again, which considerably delays processing. Therefore, the aforementioned devices are suited for continuous processing of non-interrupted surfaces, for example of the surface of a camshaft or the surface of a friction bearing. Should, however, surfaces be processed having interruptions over their circumference, other methods may have to be used.

Therefore, provided herein is a device by means of which surfaces may be processed, for example, with a superfinishing method, which are not continuous, but may have interruptions over their circumference.

Further provided is a device for superfinishing spherical shells or parts of spherical shells or flattened domes, which are provided on workpieces, and which, for example, are part of a ball joint. The device is a tool having a machining stone, with a workpiece receiver, a first drive for an oscillating motion about a first axis of the workpiece, a tool holder, and a second drive for an oscillating motion about a second axis of the tool holder, whereby the first axis and the second axis are arranged at an angle to one another.

The device has two drives, namely a drive for the workpiece or the workpiece holder and a drive for the tool, whereby both drives set the workpiece and tool into an oscillatory motion. In this way, it is assured that even in the event that interrupted surfaces are to be processed on the workpiece, the tool does not leave the processing surface since neither the workpiece nor the tool rotates. The oscillatory motions are adjusted such that the machining stone does not leave the likewise oscillating surface of the workpiece to be processed. The processing can therefore take place continuously, namely, without interruptions.

Further provided is the device wherein the axes of oscillation of the first drive and the second drive intersect at the center of the center of the sphere of the spherical shells or the flattened dome. The axes may be orthogonal to one another. In this way, the desired sinusoid curves are generated, the processing traces having been at a defined angle to one another.

The angle of oscillation of at least one of the drives may be adjusted. It is provided that the angle of oscillation of at least one of the drives may also be adjusted during processing. In this way, processing traces can be generated in the form of a figure eight, or a lying figure eight, or in the form of Lissajous curves.

In this case, for example, oscillation angles of about ±5° to about ±20°, about ±8° to about ±15°, or about ±10° may be generated. The oscillation angles for the tool drive may also be different from the oscillation angle of the workpiece drive. The drives may be coupled so that phase-shifted motions may be generated, during which the resulting processing speed never becomes zero.

In one form, the machining stone is cylindrical and has a partial spherical working surface corresponding to the shape of the flattened dome. In this case, the partial spherical working surface is advantageously situated on the frontal area of the cylinder. The cylinder may have a round, especially circular, or polygonal, e.g., rectangular or square cross section.

The machining stone may be moved in the direction of or parallel to the axis of the first drive and/or to the axis of the second drive so that it is introduced into the spherical shell or flattened dome and may be advanced to the surface to be processed.

In order to obtain the desired abrasion, the machining stone may be acted upon with a contact pressure in the direction of the axis of the first drive or orthogonally to the surface to be processed. This contact pressure is adjustable and/or may in turn be adjusted during processing.

In order to be able to process two surfaces of a spherical shell or flattened dome that are in opposite positions to one another with a single stone, the second drive is configured for the tool holder such that the machining stone may be rotated about its oscillation axis by 180° and/or such that the machining stone has two opposed working surfaces. After finishing one of the surfaces to be processed, the stone need only be displaced in the direction of the other surface to be processed.

Another version provides that the machining stone is made of several stone sections, whereby the stone sections consist of various materials. In this way, pre-machining and machining may be performed with the machining stone. Both stone sections have a working surface which, for example, have different grain sizes.

Further advantages, features and details of this disclosure will be apparent from the description and claims which follow.

DRAWINGS

In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

FIG. 1 shows a plan view of a device according to the disclosure;

FIG. 2 shows a longitudinal section of the workpiece to be processed;

FIG. 3 shows a plan view of the workpiece with an embodiment of the workpiece;

FIG. 4 shows a plan view of the workpiece with an embodiment of the tool; and

FIG. 5 shows a plan view of the workpiece with a further embodiment of the tool.

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

FIG. 1 is a plan view of the device 10, according to the disclosure, for processing surfaces, for example for superfinishing a workpiece 12, whereby the workpiece 12 is inserted into a workpiece receiver 14 of a first drive 16. The workpiece 12 is shown enlarged in FIG. 2 and has a piston 18 and a flattened dome 20 which are components of a ball joint, for example for the drive of the piston 18, and has surfaces 22 and 24 to be processed lying opposite one another and accommodate a ball of the ball joint between them. A machining stone 28 fastened on a tool holder 26 (FIGS. 3 and 4) meshes with the flattened dome 20, whereby the tool holder 26 is fastened to a second drive 30.

By means of the first drive 16, the workpiece receiver 14 and, consequently, the workpiece 12, may be driven oscillating about its longitudinal axis 32 lying perpendicular in the drawing, and indicated with the arrow 34 (see FIGS. 3 and 4).

With the second drive 30, the tool holder 26 is driven oscillating about its vertical longitudinal axis 36 in the drawings, which is orthogonal to the axis 32 and intersects the axis 32 at the center of the flattened dome 20, which is indicated with the arrow 38 (see FIGS. 3 and 4).

As is apparent from FIGS. 3 and 4, the machining stone 28 is fastened on the tool holder 26 by means of a quick-release clamping device, whereby the machining stone 28 has a cylindrical, or circular cylindrical shape, and is outfitted with a partial spherical working surface 40 on one frontal face.

FIG. 4 illustrates a second embodiment in which the machining stone has two partial spherical working surfaces 40 and 42 which oppose one another and with which surfaces 22 and 24 of the flattened dome 20 may be processed. But it is also possible to manufacture the machining stone 28 in two stone halves whereby the one stone half serves for coarse machining with the superfinishing method and the other stone half serves for fine machining with the superfinishing process.

After introducing the machining stone 28 into the flattened dome 20, which takes place by displacing the tool holder 26 in the direction of arrow 44, the tool holder 26 may in the first instance be displaced in the direction of surface 22 (arrow 46) until the working surface 40 lies on the surface to be processed 22 with a specifiable contact pressure. Subsequently, the workpiece 12 is driven oscillating in the direction of arrow 34 and the machining stone 28 is driven oscillating in the direction of arrow 38, as a result of which surface 22 is machined and machining furrows are generated in the form of a FIG. 8. The oscillation angles of the workpiece 12 and the machining stone 28 are respectively selected such that the working surface 40 does not leave the surface 22. Alternatively, however, after introducing the machining stone 28 into the flattened dome 20, the workpiece 12 may also be displaced in the direction of the machining stone 28 until it is set on the working surface 40.

After ending the machining process, in the embodiment of FIG. 3, the tool holder 26 is slightly displaced in the opposite direction of arrow 46, until the machining stone 28 lifts off from surface 22 and [is] then rotated 180° in the direction of arrow 38 so that the opposite surface 24 may be processed. After finishing surface 24, the machining stone 28 is once again displaced in the direction of arrow 46 up to the center of the flattened dome 20 and lifted off the flattened dome 20 opposite the direction of arrow 44.

There also exists the possibility of additionally moving the machining stone 28 oscillating about the axis 32 toward the workpiece 12, which is represented with arrow 48.

In the embodiment of FIG. 4, the tool holder 26 is displaced after finishing surface 22 opposite the direction of arrow 46 until the working surface 42 lies on surface 24 so that it may be processed. Alternatively, and in particular in case of two different stone halves, the tool holder 26 is rotated 180° in the direction of arrow 38 after finishing surface 22 and after lifting the machining stone 28 from surface 22 such that the surface 22 can be machined with the working surface 42 of the second stone half. Subsequently, the tool holder 26 is displaced in the opposite direction of arrow 46 until the working surface 40 lies on surface 24 so that it may be machined. Subsequently, the tool holder 26 is in turn rotated 180° in the direction of arrow 38 so that surface 24 may be machined with the working surface 42. The machining sequence may be selected in any desired manner.

A further version of the invention is represented in FIG. 5. The machining stone 28 is likewise divided in two in this embodiment, whereby a device 50 for spreading the machining stone sections is provided between the two machining stone sections. The machining stone sections may also be pressed with a definable contact pressure against the surfaces of workpiece (12) to be machined.

It is moreover apparent from FIG. 5 that a finishing band 52 may be interposed between working surface 40 and/or 42 of the machining stone 28 and the surface of the workpiece 20 to be processed. This is also possible in the other versions described above. The machining stone sections of device 50 are moved together to remove the tool 28 from the workpiece 20. By means of device 50, the machining stone sections may also be pressed against working surfaces 40 and 42 with a defined contact pressure. The finishing band 52 oscillates together with the machining stone 28 which also may merely be an element for transferring the desired shape and is made of Vulcolan®, for example.

In any case, a curved surface 22, 24 which does not extend over 360° may be machined with the device 10 according to the invention without the machining stone 28 having to be lifted from the surfaces 22, 24 to be machined during the machining process. The surface 22 or 24 to be machined as well as the working surfaces 40 and 42 of the machining stone 28 execute oscillating motions at an angle to one another. In this case, the oscillatory motions have different frequencies which, advantageously, are not whole number multiples of one another.

It should be noted that the disclosure is not limited to the embodiment described and illustrated as examples. A large variety of modifications have been described and more are part of the knowledge of the person skilled in the art. These and further modifications as well as any replacement by technical equivalents may be added to the description and figures, without leaving the scope of the present disclosure. 

1. A device for machining surfaces, comprising a tool having a machining stone with a workpiece receiver, a first drive for an oscillating motion at an angle about a first axis of the workpiece, a tool holder, and a second drive for an oscillating motion at an angle about a second axis of the tool holder, whereby the first axis and the second axis are at an angle to one another.
 2. The device of claim 1, wherein the first axis and the second axis intersect at the center of the spherical shell or the flattened dome.
 3. The device of claim 1 wherein the axes are orthogonal to one another.
 4. The device of claim 1, wherein the oscillation angle of at least one drive is adjustable.
 5. The device of claim 1 wherein the oscillation angle of at least one drive may be modified during a machining process.
 6. The device of claim 1 wherein the angle of oscillation of at least one drive is about ±5° to about ±20°.
 7. The device of claim 1 wherein the machining stone is cylindrical and has at least one partial spherical working surface.
 8. The device of claim 1 wherein the machining stone or the workpiece or the first drive may be moved in the direction of the first axis.
 9. The device of claim 1 wherein the machining stone or the first drive may be moved in the direction of the second axis.
 10. The device of claim 1 wherein the machining stone or the first drive may be acted upon by a contact pressure in the direction of the first axis.
 11. The device of claim 1 wherein the machining stone has two working surfaces opposed to one another.
 12. The device of claim 1 wherein the machining stone has two machining stone sections and each machining stone section has a working surface.
 13. The device of claim 6 wherein the angle of oscillation of at least one drive is about ±8° to about ±15°.
 14. The device of claim 6 wherein the angle of oscillation of at least one drive is about ±10°.
 15. The device of claim 12, wherein a device for spreading the machining stone sections and moving them together is provided between the machining stone sections.
 16. The device of claim 15, wherein the device for spreading the machining stone sections and moving them together presses the machining stone sections against a surface of the workpiece to be machined at a definable contact pressure.
 17. The device of claim 15 wherein a finishing band may be interposed between the machining stone and the surface of the workpiece to be machined. 